UNIVERSITY OF GUYANAFACULTY OF

TECHNOLOGY DEPARTMENT OF CIVIL

ENGINEERING

HOVERCRAFTAs modes of transportation have evolved over the years, finding more efficient and economic ways of movement have been the chief goals of developers. It is from this evolution that the hovercraft arose.

OUTLINE OF PRESENTATIONIntroductionHistoryModelsElements of a Typical hovercraftDesign ConfigurationsOperation of the HovercraftDesign ConsiderationsUse of the HovercraftEnvironmental ImpactHovercraft in GuyanaConclusion

INTRODUCTIONWhat is a Hovercraft?

A hovercraft is an amphibious vehicle that can move with equal ease on both land and water or any other terrain. It is also known as an air cushion vehicle.

INTRODUCTION

Hovercraft on land Hovercraft on water

HISTORY 1716 Emmanuel Swedenborg (Swedish Designer &

Philosopher)He first conceptualized the idea of supporting a vehicle on a cushion of air but his project was short lived and his craft never built.

Mid 1870s Sir John Thornycroft (British Engineer)He developed the air cushion effect idea further by building and testing a number of models but no applications were found since the technology to implement the concept did not exist at the time.

1952 Sir Christopher Cockerell (British Engineering)He invented the hovercraft. He found the missing link that everyone else missed. Developed the hovercraft principle further and got his idea patented in 1955. With diligent work he was able to bring his idea to reality with the first commercial hovercraft in 1959. From there on the idea took with numerous developments with the vehicle.

ModelsBritish Aircraft manufacturer Saunders Roe

SRN1The first practical model to be made. It was powered by one (piston) engine, driven by expelled air and could carry little more than its own weight and two men.

The SRN1 During Trials in 1959

ModelsSRN1

ModelsOther developments led to larger and more efficient hovercrafts which can carry passengers such as the SRN2 to SRN6.

SRN4

ModelsOther developments led to larger and more efficient hovercrafts which can carry passengers such as the SRN2 to SRN6.

SRN6

ModelsVickers VA-3This was the first true passenger carrying hovercraft.

ModelsMany companies continued the

development of the hovercraft.British Hovercraft Corporation

(Saunders Roe & Vickers) UK Cushion CraftHovermarine

ELEMENTS OF A TYPICAL HOVERCRAFTHull

This is where the driver operates the hovercraft and passengers or cargo are located. It is the main body of the hovercraft which acts as the base for attaching of the other parts.

ELEMENTS OF A TYPICAL HOVERCRAFT

Lifting SystemThis consist of a centrifugal fan attached to a motor or an engine, which provides air for the cavity underneath the craft (called the plenum chamber) and also for filling the skirts.

ELEMENTS OF A TYPICAL HOVERCRAFT

Thrust SystemThis consists of propeller or ducted fan that moves air from in front of the craft and accelerates it out the back. This accelerated mass of air then generates thrust which pushes the craft forwards.

ELEMENTS OF A TYPICAL HOVERCRAFTSkirt

This is the flexible wall that is attached all around the bottom of the craft. The skirts prevents the pressurized air from escaping from the plenum chamber.

ELEMENTS OF A TYPICAL HOVERCRAFT

EngineA typical hovercraft typically uses one engine but larger sizes can use more sometimes up to six engines. They usually utilized the typical marine engines since they are quieter and fuel efficient.

ELEMENTS OF A TYPICAL HOVERCRAFTControl System

This consists of a set of rudders that steer the craft by directing the air from the thrust system toward either left or right which consequently steers the craft.

ELEMENTS OF A TYPICAL HOVERCRAFT

Control System

ELEMENTS OF A TYPICAL HOVERCRAFTAir Box

This is a box like structure at the rear of the hovercraft located behind the propeller. It diverts some of the thrust air underneath the hovercraft.

DESIGN CONFIGURATIONSThey can be designed with one or more engines. One is used for driving the lift fan and the other used for driving the thrust fans.

Some Hovercraft use the principle of ducting to allow one engine to perform both lift and propulsion by directing some of the air to the skirt and the rest of the air is passed out of the back for thrust.

OPERATION OF THE HOVERCRAFTPrinciple of Operation

OPERATION OF THE HOVERCRAFTPrinciple of Operation

OPERATION OF THE HOVERCRAFTThe lift fan pushes a large volume of air under the hovercraft which is prevented from escaping by the skirt.As the fan continues to force air into this cushion, the pressure under the hovercraft increases. When the pressure under the hovercraft exceeds the weight of the hovercraft, the hovercraft begins to rise off the ground this can be around 6’’ to 105’’ depending on the size of the craft.Eventually the hovercraft raises high enough to lift the skirt off the ground.Air begins to escape through the gap between the ground and the skirt (called the hovergap).At some point the hovercraft reaches equilibrium point at which the amount of air being forced into the cushion can not exceed the amount of air escaping through the hovergap.At this point the hovercraft is hovering at its maximum hover height.The hover height and hovergap which result at this stage can, with certain limits, be adjusted through the design process.Fans mounted on top creates thrust air which is used to propel the hovercraft forward and moving the thrust air with rudders controls hovercraft direction.

OPERATION OF THE HOVERCRAFTBrakes & Steering

SteeringSteering is accomplished by use of the rudders. The rudders are placed at the back of the craft in the direction of the thrust air flow. As the direction of the rudders are changed so is the direction of the craft.

BrakesHovercraft have no braking system. Simply reduce power until the craft no longer hovers. Thrust reversers can be used.

OPERATION OF THE HOVERCRAFTFuel Consumption

This will depend on the speed and other conditions which the craft is driven under. But it uses less gas as compared to cars and boats under the same condition. Hovercraft speed range is about 30-75 miles per hour. A typical gasoline car averages 3.2 gallons per hour whereas an average hovercraft gets about 2.8 gallons per hour.

OPERATION OF THE HOVERCRAFT

SafetyThey have not been any major accident involving hovercrafts. Only the occasional break down due to lack of maintenance. Based upon information the hovercraft seems to be one of the safest means of transportation.

DESIGN CONSIDERATIONS

Carrying CapacityPressure = Force/AreaA bigger hovercraft, one with a bigger overall area can carry more weight than a smaller hovercraft with a fan the same size. Therefore, the surface area should be kept as large as possible reducing the pressure needed.

Aerodynamic DragThis is the force that the thrust must overcome. The drag can be reduced by reducing the frontal area of the craft.

DESIGN CONSIDERATIONSThrust

The propellers used must be able to overcome the aerodynamic drag.

SkirtsDepends on the usage of the hovercraft.

Stability The location of the various components and loadings so as not to overload any particular area which may make the craft unstable.

USE OF THE HOVERCRAFTPersonal Use

USE OF THE HOVERCRAFTSearch & Rescue

The hovercraft can travel on virtually all terrain

Hovercraft life boat

USE OF THE HOVERCRAFTSearch & Rescue

The hovercraft can travel on virtually all terrain

Hovercraft being used for a rescue operation

USE OF THE HOVERCRAFTMass Transportation

Passenger ferries (goods, vehicles)

Passenger-carrying hovercraft, off shore from Ōita Airport

USE OF THE HOVERCRAFTMass Transportation

The Hovertravel service between the Isle of Wight and mainland England is currently the only public hovercraft service in the United Kingdom

USE OF THE HOVERCRAFTRecreational Purposes

Sporting activities

A Formula 1 racing hovercraft

USE OF THE HOVERCRAFTResearch & Military uses

A U.S. Navy Landing Craft Air Cushion, an example of a military hovercraft

ENVIRONMENTAL IMPACTThe air cushion enables a hovercraft to operate over

environmentally sensitive areas such as muskeg or mudflats without disturbing the surface.

The ground pressure exerted even by a fully loaded hovercraft is so low that the craft can pass over bird eggs without breaking them.

The lack of disturbance on water minimizes the potential for bank erosion and does not disturb swimmers or canoeists.

Unlike many boats, engine exhaust fumes are not directed into the water and poisonous anti-fouling compounds are not required on hovercraft.

They require no docking mechanisms and can land safely on virtually any kind of shore.

HOVERCRAFT IN GUYANACan Hovercrafts replace speed boats?

Given that:1. Can travel over the surface of the water without

concern for the depth or hidden obstacles2. Can travel against the current of a river with no

reduction in speed3. They are unaffected by small waves and offer a

comfortable smooth ride4. Have sufficient cushion height to pass right over

a person in water5. Can come right up to the shore even if there is

no water

HOVERCRAFT IN GUYANA

CONCLUSIONThe hovercraft is in operation today throughout the world for a variety of purposes and its use is growing giving raise to new and improved designs resulting in greater applications.With its safety and adaptability it can become one of the most important and economical means of transport in the future.

THANK U!